BIOL midterm Flashcards
Matter
Anything that occupies space and
has mass
Element
A substance that cannot be broken
down to other substances by normal
Compound
A substance consisting of two or more elements
combined in a fixed ratio
Most components in living organisms are made up of at least 3 or 4
elements
Sugar = C, O, H
* Proteins = C, O, H, N, S
The number of elements necessary for life vary depending on the
organism
Humans need 25 elements
* Plants need 17 elements
The big six
make
up 99% of the matter in us
O, C, H, N, P, Ca
Other Important Elements
K, S, Na, Cl, Mg
* Used for nerve signaling and chemical reactions
Iron is needed by all forms of life
Iodine is only needed by vertebrates
Atom
Smallest unit of matter that still retains the properties of an element
The atom can be split into subatomic particles
Proton: A single positive electrical charge
* Electron: A single negative electrical charge
* Neutron: Electrically neutral
Nucleus
The central core of an atom
* Electrons form a cloud of negative charge
around the nucleus
* Negatively charged electrons are held close
to the nucleus by their attraction to the
positively charged protons
Atomic number
The number of protons in an atom
Mass number
The sum of the number of protons
and neutrons in a nucleus
Isotopes
Atoms that have the same number of protons and behave
the same way chemically but have different numbers of neutrons
Radioactive isotope
The nucleus is unstable causing it to decay
spontaneously, releasing particles and energy (radiation)
Radioactive Isotopes in Medicine
Chemical Tags
* Chemicals that accumulate in certain areas of the body can be tagged with
radioactive isotopes. A special camera can then be used to detect that
accumulation
* Treatment
* Example: Iodine accumulates in the thyroid. Thyroid cancer can be targeted
by using radioactive iodine
* Imaging of areas of the body with high levels of metabolism
* Sugars or gases can be radioactively tagged to image areas of the body that
use the molecules
Inert atoms
Atoms that have complete outer shells, don’t interact with other elements.
Chemical bonds
Attractions and interactions between atoms
Ionic bond
Transfer of electrons from one atom to another
Covalent bond
Sharing of electrons between atoms
Molecule
Two or more atoms bound together by covalent bonds
Electronegativity
An atom’s measure of attraction for shared electrons
Nonpolar covalent bonds:
Electrons are shared equally because the
two atoms have the same electronegativity
Polar covalent bonds
When two atoms have
different electronegativity the electrons will
be pulled closer to the more electronegative
element
One atom will have a slightly negative charge
and the other atom will have a slightly
positive charge
Ion
An atom with an electrical charge due to the
gain or loss of electrons
Ionic Bond Formation
When an electron is transferred from one atom to
another we are actually transferring one unit of
negative charge
Salt
Any ionic compound, many drugs manufactured as these
Hydrogen Bonds
Weak bonds within and between
molecules, they occur between polar molecules, most often attracted to
oxygen and nitrogen atoms
Chemical reaction
Breaking existing chemical bonds and forming
new ones
Reactants
Starting materials
Product
The material that results from the chemical reaction
Balanced chemical equation
2 H2 + O2 -> 2 H2O
Cohesion
The tendency of molecules of the same kind to stick
together due to hydrogen bonds
Adhesion
The clinging of one substance to another
Surface tension
The measure of how
difficult it is to stretch or break the
surface of a liquid
Thermal energy
Energy associated with the random movement of
atoms and molecules
Heat
Thermal energy transferring from a warmer body of matter to a
cooler body of matter
Temperature
The measure of the intensity of heat. The average
speed of molecules in a body of matter
Temperature Moderation
Warm molecules move more quickly than cold
molecules
* Hydrogen bonds need to be broken to allow
molecules to move more quickly
* Heat must be absorbed to break hydrogen bonds
* Water absorbs a large amount of heat to break its
bonds before temperature actually increases
* When water cools it releases a lot of heat
Evaporation
The change of a substance from liquid state to gas state
Evaporative cooling
When evaporation occurs, the liquid that
remains are, on average, cooler than it was before
Solid Water is Less Dense Than Liquid Water
Hydrogen bonds
* Hydrogen bonds are relatively
weak and unstable
* As water freezes the hydrogen
bonds are stabilized and each
molecule keeps the others “at arms
length”
Solution
A liquid consisting of a uniform mixture of two or more substances
Solvent
The dissolving agent
Solute
A substance that is dissolved
Aqueous solution
A solution in which water is the solvent
Water Dissolves Ionic Compounds
Water can dissolve any ionic compound
* Example: NaCl dissolved in H2O
* Positive H atoms are attracted to Cl- ions
* Negative O atoms are attracted to Na+ ions
* Water molecules will therefore surround and
separate every single ion in a grain of salt
Water Dissolves Non-Ionic Compounds
Large molecules such as proteins can also be dissolved if they have
ionic or polar regions on their surfaces
Water will surround the compound and form hydrogen bonds with the polar
regions
Acids and Bases
Some chemical compounds contribute H+ to a solution and others
take H+ out of solution
Acid
A substance that donates H+ to a solution
Base
A substance that reduces the amount of H+ in a solution
pH and Our Bodies
pH in most of our cells is close to 7.0
* pH of our blood is 7.4
* A human will die in minutes if the pH of the blood goes as low as 7.0 or as
high as 7.8
Buffer
help us maintain a constant pH in our bodies
Carbon
Almost all the molecules in a cell are
composed of carbon bound together and
bound to other elements
* These molecules form the structure of cells
and carry out the cellular functions
Organic compounds
Carbon based molecules
* Usually contain hydrogen atoms bound to the
carbon atoms
shape determines what?
The shape of a molecule usually determines its function
Carbon skeleton
The chain of
carbon atoms
that forms the
backbone of an
organic molecule
Isomers
Compounds with the same chemical formula but different
structural arrangements
Hydrocarbons:
Molecules that consist of only carbon and hydrogen,
major component in fossil fuels
Chemical group
Atoms that are attached to the
carbon skeleton, chemical groups affect the function
Hydroxyl
Alcohols
OH
Carbonyl
These can donate an H+ to a solution
making it acidic. These are called carboxylic acids
C=O
Carboxyl
These can donate an H+ to a solution
making it acidic. These are called carboxylic acids
COOH
Amino group
Pick up an H+ from solution to
become ionized and are called amines
NH2
Phosphate
Often ionized because O atoms
are negative. These organic phosphates are
involved in energy transfers
OPO3^2
Methyl group
Affects the expression of genes.
CH3
Functional groups
Chemical groups that affect a
molecule’s function by participating in chemical
reactions
Polar groups
Makes the molecules hydrophilic (water soluble)
* Important when a cell is composed mostly of water
* Hydroxyl, carbonyl, carboxyl, amino, and phosphate groups
Non-polar group
Makes the molecule hydrophobic (not water soluble)
* Methyl group
* Not reactive, not water soluble
* Affects shape of the molecule
Classes of Molecules
Carbohydrates, lipids, proteins, nucleic acids
Macromolecules
Very large molecules
* Carbohydrates, lipids, proteins, and nucleic acids
Polymers
Small molecules joined together in chains
* Macromolecules are made of large polymers
* Long molecule consisting of many identical or similar building blocks all strung
together in a chain
Monomers
The building blocks of polymers
Dehydration reaction
Removes a
molecule of water as two molecules
become bonded together
Making Polymers
Monomers are linked together using
a dehydration reaction
Breaking Polymers
Polymers are broken back into
monomers to be recycled by the cell
Hydrolysis
The digestion of polymers
into monomers
* Opposite of a dehydration reaction
Diversity of Polymers
All forms of life use the exact same ingredients
* Proteins are made from only 20 amino acids
* DNA is made from only 4 different monomers called nucleotides
* Arrangement of the monomers is the key to the diversity of polymers
Macromolecule #1: Carbohydrates
Sugars
* Can be small molecules, can be large molecules most carbohydrates are hydrophilic,
Monosaccharides
Simple sugars, chemical formula is generally a
multiple of CH2O,Sugars typically contain a carbonyl
group and multiple hydroxyl groups
Monosaccharides
Simple sugars, chemical formula is generally a
multiple of CH2O,sugars typically contain a carbonyl
group and multiple hydroxyl groups
Monosaccharides Form Rings
Monosaccharides can have anywhere
from three to seven carbons atoms in
their carbon skeleton
Sugars (carbohydrates)
Most sugar names end in ‘ose’
* Enzymes that break sugars apart end in ‘ase’,energy is released when they are broken down, the cell can
immediately use that energy for other processes
Disaccharides
two monosaccharides linked together
using a dehydration reaction
Polysaccharides
Macromolecules
* Hundreds or thousands of monosaccharides linked together
* Function as storage molecules or structural compounds
Starch
* Glycogen
* Cellulose
* chitin
Starch
Storage polysaccharide in plants, Used as a carbohydrate bank
* Plants can withdraw glucose units for energy and building materials
Glycogen
Glucose storage molecule in animals
* Highly branched
* Primarily stored in your liver and muscles cells
* Liver and muscle cells can hydrolyze glycogen to release glucose
molecules when needed
Cellulose
Polymer of glucose
* Arranged in cable-like microfibrils (layers of strings)
* Most abundant organic compound on earth
Animals cannot break down cellulose
Macromolecule #2 - Lipids
All are hydrophobic (they do not mix well with water), 3 important types of lipids
* Fats, phospholipids, steroids
Fat
Large lipid consisting of two smaller molecules –
glycerol and fatty acids
* Fatty acid: Carboxyl group bound to a hydrocarbon
chain (usually 16 or 18 carbons long), 3 fatty acids linked to a glycerol molecule make a fat
Unsaturated fatty acid
A hydrocarbon chain has
one or more double bond
Remain liquid at room temperature
Saturated fatty acid
A hydrocarbon chain that has
only single bonds, solid at room temp
Partially hydrogenated oils
Unsaturated fats that have been converted to
saturated fats
Fat storage
Main function of fats is energy storage
* A gram of fat stores twice as much energy as a gram of carbohydrates
* Plants store most of their energy as carbohydrates
* Animals store their energy as fats
Phospholipids
Major component of cell membranes
* Life could not exist without phospholipids
* Similar in structure to fats
Arrange themselves in a double
layered sheet
* Fatty acid tails in the middle
* Glycerol heads on the outside
* This is how membranes are
formed
Steroids
Carbon skeleton contains 4 fused rings
* Different steroids vary in the chemical groups attached to them
Macromolecule #3 - Proteins
Protein: Polymer of small building blocks called amino acids
* Almost all functions in your body depend on proteins
* Structurally and functionally the most varied and elaborate molecules in living
organisms
Transport molecules
Import and export nutrients and wastes from the
cells
Defense proteins
Antibodies in the blood stream
Signaling proteins
Coordinate your body’s activities
Receptor proteins
Receive and transmit signals on the cell surface
Contractile proteins
are in your muscles
Structural proteins
Make up your tendons, ligaments and connective
tissue
Storage proteins
Supply amino acids to developing embryos
Fibrous proteins
Structural proteins are often fibrous
* These make up hair, tendons and ligaments
* The shape of the protein makes the filament very strong
Globular proteins
Most enzymes and many other proteins
Protein Shape
Each protein has a specific, unique shape
* Proteins must recognize and bind to other molecules to function
Denaturation
Process where a protein unravels and loses its shape
and therefore, its function, can be caused by heat
Incorrect Folding
Often this causes diseases
Prions
Infectious misshapen proteins associated with degenerative
brain diseases
Amino Acids
The building blocks of proteins
Peptide bond
Dehydration reaction forms between the carboxyl
group of one amino acid and the amino group of the other amino acid
Dipeptide
Molecule (or peptide) made of two amino acids
Polypeptide
A chain of amino acids
Polypeptides are Not Complete Proteins
A polypeptide must be coiled and folded into its final shape to make a
protein
Primary structure
Sequence of amino acids in a polypeptide chain
Secondary structure
Segments of the polypeptide chain coil and fold
into regional patterns
Tertiary structure
The overall 3D shape of the folded polypeptide
Quaternary structure
Some proteins consist of more than one
polypeptide chain. The chains are each called a subunit. The subunits
interact with each other in the quaternary structure to form the
completed protein
Gene
The unit of inheritance that determines the amino acid
sequence of a polypeptide
DNA (deoxyribonucleic acid)
The nucleic acid that a gene is made of
RNA (ribonucleic acid)
Nucleic acid that assembles the polypeptide
according to the instructions in DNA
Nucleotides
The monomers that make up nucleic
acids
Nitrogenous base
Structure that contains nitrogen
and carbon
Nitrogenous bases in DNA are
adenine (A), thymine (T), Guanine (G), and cytosine (C)
Nitrogenous bases in RNA are
A, G, C, and uracil (U)
Polynucleotide
Polymer built from nucleotide
monomers
Nucleic Acid Structure
RNA consists of a single polynucleotide strand
* DNA consists of two polynucleotide strands that wind around
each other in a double helix
Gene expression
The production of proteins using the instructions
found in DNA
Transcription
A gene in DNA directs the synthesis of an RNA molecule
